History is about how things happen in time, but most of us remain unaware that time itself has a history. We learn to orient ourselves in the “one and only” public time of our social life without realizing that it is a historical construct, as culturally variable as hairstyles and hemlines. Even for most professional historians, time itself—the unique dynamic context of their discipline—remains pre-reflective and pre-thematic; that is, historians do not think about time's own historicality and have no language to describe it.